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    • 领扣:423. Valid Parentheses

      423. Valid Parentheses

      Given a string containing just the characters '(', ')''{''}''[' and ']', determine if the input string is valid.

      The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]" are not.

      Example

      Example 1:

      Input: "([)]"
      Output: False

      Example 2:

      Input: "()[]{}"
      Output: True

      Challenge

      Use O(n) time, n is the number of parentheses.

      class Solution:
          """
          @param s: A string
          @return: whether the string is a valid parentheses
          """
          def isValidParentheses(self, s):
              # write your code here
              valarr = []
              for each in s:
                  print(valarr)
                  if each == '{':
                      valarr.append('{')
                  if each == '(':
                      valarr.append('(')
                  if each == '[':
                      valarr.append('[')
                  
                  if each == '}':
                      if len(valarr) == 0 or valarr.pop() != '{':
                          return False
                  if each == ')':
                      if len(valarr) == 0 or valarr.pop() != '(':
                          return False
                  if each == ']':
                      if len(valarr) == 0 or valarr.pop() != '[':
                          return False
                          
              if len(valarr) == 0:
                  return True
              else:
                   return False

      纽约州·纽约
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